1. Field of the Invention
This invention relates to an array of bistable devices, and to apparatus for and methods of creating same. Accordingly, it is a general object of this invention to provide new and improved arrays, apparatus and methods of such character.
2. General Background
We propose a new technique or making a 2-dimensional spatial light modulator based on cavityless optical bistability that reduces the effects of heat diffusion and crosstalks, thus making it possible to spatially distribute optical bistable devices in a 2-dimensional plane in a pre-selected and controlled manner.
Two-dimensional spatial light modulators should play an important role in all-optical signal processing applications (such as image processing), optical computation, and in making optical interconnections among electronic and electro-optic systems. Two-dimensional arrays of optical bistable devices can be used as all-optical two-dimensional spatial light modulators. Optical switching, optical logic operations, limiting, AC amplification, and modulation have already been demonstrated using optical bistable devices. However, in conventional optical bistable devices, the requirement for a cavity and some type of external optical feedback puts serious restrictions on the ease of fabricating the devices. Very often, reflective coatings have to be deposited, and distributed feedback structures have to be provided which add to the complexity of the fabrication process. Earlier, two of us have filed a copending U.S. patent application Ser. No. 06/713,510 on Mar. 19, 1985 now abandoned on an optical bistable device. That device is cavityless and is based on induced absorption. This induced absorption comes from a thermal shift of a sharp resonance or absorption edge in a semiconductor. In addition to the ease of fabrication, this new optical bistable device has the important advantages that its output is very stable (no self-pulsation) under cw conditions and is very reproducible. However, in order to use such a device, in two-dimensional arrays, it is necessary to reduce the crosstalk between the devices. As the principle of operation of this bistable device is based on optical heating, and as heat can diffuse, it is desirable to minimize the amount of heat deposited into the sample.